释义 |
Helmholtz Differential Equation--Elliptic Cylindrical CoordinatesIn Elliptic Cylindrical Coordinates, the Scale Factors are , , and the separation functions are , giving aStäckel Determinant of . The Helmholtz differentialequation is
 | (1) |
Attempt Separation of Variables by writing
 | (2) |
then the Helmholtz Differential Equation becomes
 | (3) |
Now divide by to give
 | (4) |
Separating the part,
 | (5) |
so
 | (6) |
which has the solution
 | (7) |
Rewriting (5) gives
 | (8) |
which can be separated into
so
 | (11) |
 | (12) |
Now use
 | (13) |
 | (14) |
to obtain
 | (15) |
 | (16) |
Regrouping gives
 | (17) |
 | (18) |
Let and , then these become
 | (19) |
 | (20) |
Here, (20) is the Mathieu Differential Equation and (19) is the modified Mathieu DifferentialEquation. These solutions are known as Mathieu Functions.See also Elliptic Cylindrical Coordinates, Mathieu Differential Equation, Mathieu Function References
Morse, P. M. and Feshbach, H. Methods of Theoretical Physics, Part I. New York: McGraw-Hill, pp. 514 and 657, 1953. |